Generally, antennas installed in mobile terminals including mobile communication functions may be largely divided into external antennas and embedded antennas according to installation positions.
A whip type antenna, a helical type antenna, and the like are mainly used as an external antenna. The external antenna has a structure which is inserted and removed by a user by being fixedly installed at a side surface or an upper portion of the mobile terminal.
Since the above external antenna is installed outside the mobile terminal, the mobile terminal is difficult to use and keep, and an exterior of the mobile terminal may be damaged. Further, since an installation space for the external antenna should be ensured at the outside of the mobile terminal, there may be a constraint on an exterior design of the mobile terminal, the design may be damaged and it is difficult to miniaturize and slim the mobile terminal.
In order to compensate for the above-described disadvantages of the external antenna, an embedded antenna method in which an antenna is installed inside a mobile terminal is mainly being used in recent years.
A monopole type antenna, a loop type antenna, or a planar inverted-F antenna (PIFA) is used as the embedded antenna (or an intenna). Since the embedded antenna is installed inside the mobile terminal, a space in which the embedded antenna may be installed should be provided at the inside of the mobile terminal. The installation space of the embedded antenna is reduced as the mobile terminal is slimmed or miniaturized.
Further, recently, as mobile terminals are being slimed and miniaturized, the number of mobile terminals which have an external case formed of a metal material for robustness and elegant, design of the mobile terminal is increased.
However, a metal structure makes radiation of an antenna difficult, and may handle only a limited band even when the antenna is implemented. Therefore, in the mobile terminal having a metal structure, the metal case is being limitedly applied to only a portion other than an antenna area.